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For the multi-label classification task of remote sensing images (RSIs), it is difficult to accurately extract feature information from complex land covers, and it is easy to generate redundant features by ordinary convolution extraction features. This paper proposes a multi-label classification model for multi-source RSIs that combines dense convolution and an attention mechanism. This method adds fusion channel attention and a spatial attention mechanism to each dense block module of the DenseNet, and the sigmoid activation function replaces the softmax activation function in multi-label classification. The improved model retains the main features of RSIs to the greatest extent and enhances the feature extraction of the images. The model can integrate local features, capture global dependencies, and aggregate contextual information to improve the multi-label land cover classification accuracy of RSIs. We conducted comparative experiments on the SEN12-MS and UC-Merced land cover dataset and analyzed the evaluation indicators. The experimental results show that this method effectively improves the multi-label classification accuracy of RSIs. [ABSTRACT FROM AUTHOR]

A novel pH-sensitive polystyrene (PS)-type resin was developed by grafting of poly(3-sulfopropyl methacrylate) (PSPMA) brushes onto a cross-linked poly(vinylbenzyl chloride) (PVBC) microsphere via surface-initiated atom transfer radical polymerization (ATRP), and was further utilized as a highly efficient and recyclable sorbent to remove Pb(II) ions from aqueous solutions. The as-synthesized PSPMA-grafted PVBC microspheres were characterized by ATR-FTIR, XPS and SEM. Batch adsorption results revealed that the solution pH had an evident effect on the adsorption capacity of the PSPMA-grafted microspheres towards Pb(II) ions with an optimal sorption pH of above 5.0. The PSPMA-grafted microspheres had rapid adsorption kinetics of Pb(II) ions to reach adsorption equilibrium within 60 min. The Langmuir-fitted adsorption isotherms at pH 5.0 with an initial Pb(II) concentration range of 0.12–0.97 mmol L −1 (i.e. 50–200 mg L −1 ) revealed a maximum capacity of Pb(II) ions of 0.82 mmol g −1 . The calculated thermodynamic parameters demonstrated an endothermic and spontaneous adsorption process of Pb(II) ions on the PSPMA-grafted microspheres. With the inherent stability, high adsorption capacity and good regenerability, the PSPMA-grafted PVBC microsphere resin provides a novel promising PS-type adsorbent for effective removal of heavy metal ions from aqueous solution. [ABSTRACT FROM AUTHOR]

Establishing crop cultivars with strong tolerance to P and N deprivation, high salinity, and drought is an effective way to improve crop yield and promote sustainable agriculture worldwide. A vacuolar H+-pyrophosphatase (V-H+-PPase) gene in wheat (TaVP) was functionally characterized in this study. TaVP cDNA is 2586-bp long and encodes a 775-amino-acid polypeptide that contains 10 conserved membrane-spanning domains. Transcription of TaVP was upregulated by inorganic phosphate (Pi) and N deprivation, high salinity, and drought. Transgene analysis revealed that TaVP overexpression improved plant growth under normal conditions and specifically under Pi and N deprivation stresses, high salinity, and drought. The improvement of growth of the transgenic plants was found to be closely related to elevated V-H+-PPase activities in their tonoplasts and enlarged root systems, which possibly resulted from elevated expression of auxin transport-associated genes. TaVP-overexpressing plants showed high dry mass, photosynthetic efficiencies, antioxidant enzyme activities, and P, N, and soluble carbohydrate concentrations under various growth conditions, particularly under the stress conditions. The transcription of phosphate and nitrate transporter genes was not altered in TaVP-overexpressing plants compared with the wild type, suggesting that high P and N concentrations regulated by TaVP were caused by increased root absorption area instead of alteration of Pi and NO3− acquisition kinetics. TaVP is important in the tolerance of multiple stresses and can serve as a useful genetic resource to improve plant P- and N-use efficiencies and to increase tolerance to high salinity and drought. [ABSTRACT FROM PUBLISHER]

Drought is an important factor limiting plant development and crop production. Dissecting the factors involved in this process is the key for enhancement of plant tolerance to drought stress by genetic approach. Here, we evaluated the regulatory function of a novel rice ethylene response factor (ERF) OsERF109 in drought stress. Expression of OsERF109 was rapidly induced by stress and phytohormones. Subcellular localization and transactivation assay demonstrated that OsERF109 was localized in nucleus and possessed transactivation activity. Transgenic plants overexpressing (OE) and knockdown with RNA interfering (RI) OsERF109 exhibited significantly reduced and improved drought resistance, respectively, indicating that OsERF109 negatively regulates drought resistance in rice. Furthermore, measurement by gas chromatography showed that ethylene contents were less in OE while more in RI lines than these in wild types, supporting the data of drought tolerance and water loss in transgenic lines. Quantitative real-time PCR analysis also proved the regulation of OsERF109 in the expression of OSACS6, OSACO2, and OsERF3, which have been identified to play important roles in ethylene biosynthesis. Based on these results, our data evidence that OsERF109 regulates drought resistance by affecting the ethylene biosynthesis in rice. Overall, our study reveals the negative role of OsERF109 in ethylene biosynthesis and drought tolerance in rice. [ABSTRACT FROM AUTHOR]

microRNAs (miRNAs) are involved in regulating various plant developmental processes and mediating plant-adaptive responses to nutrient deprivation. In this study, the characterization of a wheat miRNA member TaMIR444a and the role of this miRNA in mediating plant tolerance to the N-starvation stress were investigated. Results indicated that the expression levels of TaMIR444a and NtMIR444a, the homologue of TaMIR444a in tobacco, were upregulated in roots and leaves under N deprivation, whereas the transcription of their target genes showed reverse expression patterns in above tissues. These results suggest that miR444a is conserved across plant species of dicots and monocots and can possibly establish the miRNA/target modules for mediating plant response to N deficiency. Overexpression of TaMIR444a in tobacco improved the plant growth feature, biomass, N content, photosynthetic parameters, and antioxidant enzymatic activities under N deprivation. Based on microarray analyses, a large number of genes were identified to be differentially expressed in the TaMIR444a-overexpressing plants; these differential genes are categorized into functional groups of signal perception and transduction, transcription regulation, primary and secondary metabolism, phytohormone response, cellular protection and defensive responsiveness, etc. qPCR analyses revealed that the nitrate transporter (NRT) genes NtNRT1.1-s, NtNET1.1-t, and NtNRT2.1 and the antioxidant enzyme genes (AEEs) NtCAT1;1, NtPOD1;3, and NtPOD4 were significantly upregulated by TaMIR444a, suggesting that the altered transcription of these NRT and AEE genes is associated with the improvement of the N acquisition and the cellular ROS detoxification in the N-deprived transgenic plants. Together, our findings demonstrate that miR444a acts as one critical regulator in mediating plant tolerance to the N-starvation stress through modulation of the regulatory networks associated with N acquisition, cellular ROS homeostasis, and carbon assimilation. Our findings have provided insights into the mechanisms of plant tolerance to N deficiency mediated by the distinct miRNA pathways. [ABSTRACT FROM AUTHOR]

Abstract: Salt stress is one of the major abiotic stresses affecting plant growth, development, and productivity. In this study, we functionally characterized a wheat vacuolar Na+/H+ antiporter gene (TaNHX3). TaNHX3 is 78.9% identical with TaNHX2 in nucleic acid level, encoding a polypeptide of 522 amino acids (aa). TaNHX3 is targeted onto tonoplast after ER sorting and can complement the growth under salt stress in a yeast mutant with a defective vacuolar Na+/H+ antiporter exchange. TaNHX3 transcripts were induced by applying salt stress in wheat cultivars. More TaNHX3 were detected in the salt-stress-resistant cultivar Ji 7369 compared with the salt-stress-sensitive cultivar Shimai 12 and Ji-Shi-3, an isogenic line derived from aforementioned cultivars with Shimai 12 genetic background. The ectopic TaNHX3 expression in tobacco significantly enhanced the plant tolerance to salt stress. Compared with control plants, the TaNHX3 overexpressing plants displayed no varied Na+ contents and accumulated more Na+ amount in plants. However, they exhibited higher fresh and dry weights, more accumulative nitrogen, phosphorus, and potassium, higher contents of chlorophyll, carotenoid, soluble protein, higher activities of the antioxidant enzymes including superoxide dismutase, catalase, and peroxidase, and lower malondialdehyde and H2O2 amount. Our results indicated that TaNHX3 plays an important role in regulating the cytosolic Na+ transportation within vacuoles under high salinity, alleviating the Na+ damage effects. The improved salt stress tolerance in TaNHX3 overexpressing tobacco plants is closely associated with the improvement of the aforementioned physiological processes. TaNHX3 can be used as a candidate gene for molecular breeding of salt-tolerant plants. [Copyright &y& Elsevier]

During germination, phytate, a major phosphate compound in seeds, is degraded into inorganic phosphorus (Pi) for differentiation of new tissues via catalysis. OsPHY1, a member of phytase genes in rice, has previously been found to show high expression levels in the endosperm and hypocotyl during germination and is involved in the degradation of seed phytate. In this study, we investigated the transcriptional mechanisms of OsPHY1 via OsPHY1 promoter- GUS analysis. The results of GUS histochemical staining and activities in tobaccos harboring OsPHY1- GUS reveal that the reporter gene is strongly expressed in the hypocotyl and responds to diverse stimuli cues initiated by phytohormones abscisic acid (ABA), gibberellin (GA 3), and indole-3-acetic acid (IAA), as well as osmotic stresses of salt, drought, and cold. The results indicate that the cis-regulatory element CANBNNAPA regulates gene hypocotyl-predominant expression. ABRE and GAREAT are involved in gene responses to ABA and GA 3, respectively, and DRECRTCOREAT is involved in gene responses to stresses of salt, drought, and cold. In addition, the responses of OsPHY1 and part-osmotic stress-responsive genes to salt, drought, and cold mediated by DRECRTCOREAT are largely accomplished through the ABA-dependent pathway with the involvement of the ABA responsive cis-regulatory element ABRE. Our results reveal that the degradation of seed phytate during germination mediated by OsPHY1 is regulated in a fine-tune manner with the involvement of diverse cis-regulatory elements at the transcription level. [ABSTRACT FROM AUTHOR]

Protein phosphorylation-dephosphorylations are major signaling events induced by osmotic stress in plants. In this study, a wheat SNF1-related protein kinase 2 (SnRK2) gene, TaSRK2C1, was functionally characterized. The results from the sequence analysis showed that TaSRK2C1 contains conserved domains typified in SnRK2 protein kinases, including the ATP binding site, N-myristoylation site, protein kinase-activating signature, and transmembrane-spanning region. The transcripts of TaSRK2C1 in roots were induced by treatments of dehydration, high salinity, low temperature, and exogenous abscisic acid, which suggest its potential roles relative to osmotic stress signal transductions. The ectopic expression of TaSRK2C1 in tobacco significantly up-regulated the expression levels of three putative central regulators, namely, RD29a, DREB1A, and DREB2, which are involved in responding to osmotic stresses. Thus, higher levels of free proline and soluble carbohydrates in transgenic plants were detected, and conferred tolerance to high salinity, dehydration stress, and low temperature in plants. The overall results in this study indicate that TaSRK2C1 have important functions in plant response and adaptation to osmotic stresses via mediation of signal transductions initiated by distinct abiotic stresses. Manipulating TaSRK2C1 toward improving the osmotic-stress tolerance in crop plants is feasible. [ABSTRACT FROM AUTHOR]